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INTRODUCTION

Objectives

By studying this chapter, you should be able to do the following:

  1. Discuss the general organization of the nervous system.

  2. Describe the structure and function of a nerve.

  3. Draw and label the pathways involved in a withdrawal reflex.

  4. Define depolarization, action potential, and repolarization.

  5. Discuss the role that proprioceptors play in kinesthesia.

  6. Describe the role of the vestibular apparatus in maintaining equilibrium.

  7. Discuss the areas of the brain involved in voluntary control of movement.

  8. Describe the structure and function of the autonomic nervous system.

  9. Discuss the impact of regular endurance exercise on maintaining brain health and reducing the risk of age-related memory loss.

Outline

General Nervous System Functions

Organization of the Nervous System

  • Structure of the Neuron

  • Electrical Activity in Neurons

Sensory Information and Reflexes

  • Joint Proprioceptors

  • Muscle Proprioceptors

Muscle Chemoreceptors

Somatic Motor Function and Motor Neurons

Vestibular Apparatus and Equilibrium

Motor Control Functions of the Brain

  • Cerebrum

  • Cerebellum

  • Brain Stem

Motor Functions of the Spinal Cord

Control of Motor Functions

Autonomic Nervous System

Exercise Enhances Brain Health

Key Terms

action potential

afferent fibers

autonomic nervous system

axon

brain stem

cell body

central nervous system (CNS)

cerebellum

cerebrum

conductivity

dendrites

efferent fibers

excitatory postsynaptic potentials (EPSPs)

Golgi tendon organs (GTOs)

homeostasis

inhibitory postsynaptic potential (IPSP)

irritability

kinesthesia

motor cortex

motor neuron

motor unit

muscle spindle

neurons

neurotransmitter

parasympathetic nervous system

peripheral nervous system (PNS)

proprioceptors

reciprocal inhibition

resting membrane potential

Schwann cells

size principle

spatial summation

sympathetic nervous system

synapses

temporal summation

vestibular apparatus

The nervous system provides the body with a rapid means of internal communication that allows us to move about, talk, and coordinate the activity of billions of cells. Thus, neural activity is critically important in the body’s ability to maintain homeostasis. This chapter will provide an overview of the nervous system, with emphasis on neural control of voluntary movement. We will begin with a discussion of the general function of the nervous system.

GENERAL NERVOUS SYSTEM FUNCTIONS

The nervous system is the body’s means of perceiving and responding to events in the internal and external environments. Receptors capable of sensing touch, pain, temperature changes, and chemical stimuli send information to the central nervous system (CNS) concerning changes in our environment (5). The CNS can respond to these stimuli in several ways. The response may be involuntary movement (e.g., rapid removal of a hand from a hot surface) or alteration in the rate of release of some hormone from the endocrine system (see Chap. 5). In addition to integrating body activities and controlling voluntary movement, the nervous system is responsible for storing experiences (memory) and establishing patterns of response based on previous experiences (learning). Let’s begin our discussion of the nervous system by reviewing the general organization.

ORGANIZATION OF THE NERVOUS SYSTEM

Anatomically, the nervous system can be ...

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